Aptitude - Volume and Surface Area - Discussion
Discussion Forum : Volume and Surface Area - General Questions (Q.No. 1)
1.
A right triangle with sides 3 cm, 4 cm and 5 cm is rotated the side of 3 cm to form a cone. The volume of the cone so formed is:
12
cm3
cm315 cm3
cm316 cm3
cm320 cm3
cm3Answer: Option
Explanation:
Clearly, we have r = 3 cm and h = 4 cm.
 Volume = |
1 | r2h = |
 |
1 | x x 32 x 4 |
 cm3 |
= 12 cm3. |
| 3 | 3 |
Video Explanation: https://youtu.be/Njsid2mVwUY
Discussion:
77 comments Page 2 of 8.
Red Anca said:
7 years ago
I think the h=3 due to the problem rotated about 3cm..and the base or raduis will be r=4cm,
We can redirect to the formula;
V=1/3 * 3.141592654 * r'2 * h,
V=1/3 * 3.141592654 * 4'2 * 3.
V = 50.26 cm'3.
We can redirect to the formula;
V=1/3 * 3.141592654 * r'2 * h,
V=1/3 * 3.141592654 * 4'2 * 3.
V = 50.26 cm'3.
Rohit said:
1 decade ago
The only possible explanation is that it is rotated about, not revolved about.
If 5th rotates it means it runs around a fixed center. It rotates about 3 cm side means the 3 cm side is rotating.
If 5th rotates it means it runs around a fixed center. It rotates about 3 cm side means the 3 cm side is rotating.
Bryan Roger said:
1 year ago
The BASE would be 4 and the HEIGHT would be 3. Because the side of 3cm is rotated, that is the height.
The final answer would be 16π cm^3 on solving using the formula 1/3 (π) (r^2) h.
The final answer would be 16π cm^3 on solving using the formula 1/3 (π) (r^2) h.
(2)
Gopi said:
8 years ago
If base radius of a cone is increased by 20% and its slant height is made double then by how much percent will the area of its curved surface be increased?
a) 140% b) 110% c) 120% d) 130%
a) 140% b) 110% c) 120% d) 130%
Aakriti said:
9 years ago
1. A triangle with these dimensions doesn't form a cone.
2. Even if it does then the length of the side rotated would be the circumference of the base of the figure and not the radius.
2. Even if it does then the length of the side rotated would be the circumference of the base of the figure and not the radius.
Dikshant said:
8 years ago
Firstly, we are rotating it not folding it ok we can make a cone by rotating base by 360 degree and the second one is we always follow a sequence in maths base, height and hypotenuse.
Vish said:
10 years ago
Guys, they said triangle is rotated the 3 cm side to form a cone. So the only way the cone can b formed from a right angle triangle is by rotating base and its 3 cm in this case!
King said:
1 decade ago
The Triangle is rotated about the side 3 so it should be the height and the radius should be 4 and According to volume formula to cone its (1/3)*pi*r*r*h in should be 16*pi.
Vinay vidhani said:
1 decade ago
We know that long side in right angle triangle is hypotenuses OK let 3 is base and 4 is a height then put the formula of volume of cone is 1/3 *pai r*r*h that's all.
Ankush said:
1 decade ago
If the cone is made by rotating the side which is 3 then 3 will become the circumference of the base being 2pie r. Hence 2pie r = 3 and r = 3/2pie.
Is it correct?
Is it correct?
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